JP4003700B2

JP4003700B2 - 6-wire 3-phase brushless motor controller

Info

Publication number: JP4003700B2
Application number: JP2003156630A
Authority: JP
Inventors: 重俊大道寺; 浩横溝
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 2003-06-02
Filing date: 2003-06-02
Publication date: 2007-11-07
Anticipated expiration: 2023-06-02
Also published as: JP2004364359A

Description

【０００１】
【発明の属する技術分野】
本発明は、直流ブラシレスモータをセンサレスで駆動する直流ブラシレスモータ制御装置に関する。
【０００２】
【従来の技術】
【特許文献】
特開２０００−２３６６９１号公報。
【０００３】
上記特許文献においては、一般的なＹ結線の直流ブラシレスモータのセンサレス駆動方式として、通電していない相に誘起する誘起電圧を検出し、誘起電圧のゼロクロス点を検出することによって、通電する相を切替えるタイミングを割り出していた。
【０００４】
【発明が解決しようとする課題】
この従来例におけるゼロクロス点検出方法では、Ｈ型ブリッジ回路を３相の各相毎に備えた直流３相ブラシレスモータ（以後６線式３相ブラシレスモータと称す）では、通電していない相に誘起する誘起電圧が、Ｙ結線の直流３相ブラシレスモータにおける通電していない相に誘起する本来の誘起電圧と、通電中の他の相に流れる電流の不一致により誘起する電圧との合成となるため、ゼロクロス点がずれ、相の切替え点がずれてしまうという問題があった。
【０００５】
本発明は上述の課題を解決するためになされたもので、６線式３相ブラシレスモータでも、正確な相切替えが行える直流ブラシレスモータ制御装置を提供することを目的としている。
【０００６】
【課題を解決するための手段】
この目的を達成するために、本発明においては、通電されていない相の電機子巻線に発生する誘起電圧を検出する誘起電圧検出手段と、この誘起電圧検出手段によって検出された誘起電圧が増加から減少、もしくは減少から増加に転じた事を検出する頂点検出手段と、この頂点検出手段によって誘起電圧が増加から減少、もしくは減少から増加に転じた時からの誘起電圧の変化量が所定の変化量閾値以上となった場合に通電相を切り替える相切替手段を備えた構成とした。
【０００７】
【発明の効果】
本発明によれば、通電されていない相に発生する誘起電圧を検出する誘起電圧検出手段と、検出された誘起電圧が増加から減少、もしくは減少から増加に転じた事を検出する頂点検出手段と、誘起電圧が頂点から減少、もしくは増加に転じた時からの誘起電圧の変化量が所定の変化量閾値以上となった場合に通電相を切り替える相切替手段によって正確に通電相を切替えることができる。
【０００８】
【発明の実施の形態】
以下、図面を用いて本発明の実施の形態について説明する。なお、以下で説明する図面で、同一機能を有するものは同一符号を付け、その繰り返しの説明は省略する。
【０００９】
本発明の第１の実施の形態について、図１〜１１、表１〜３を用いて説明する。図１は本発明の第１の実施の形態の概略的な全体構成を示す構成図である。この図１を用いて第１の実施の形態の構成を説明する。６線式３相ブラシレスモータ（以下、モータと称す）１は、固定子であるＵ、Ｖ、Ｗ相の電機子巻線（以下、巻線と称す）２−１、２−２、２−３と、ロータである永久磁石（図示せず）から構成される。各相の巻線２−１、２−２、２−３は、例えばＵ相においては、一方が駆動用電源１６に接続されている上アーム側スイッチング素子（図１ではＩＧＢＴを使用）Ｕ＿Ｌ＿ＨおよびＵ＿Ｒ＿Ｈと、一方が接地されている下アーム側スイッチング素子Ｕ＿Ｌ＿ＬおよびＵ＿Ｒ＿Ｌの上下アーム側スイッチング素子をそれぞれ直列に接続し、その接続中点同士を巻線２−１を介して接続したＨ型ブリッジ回路を構成し、このＨ型ブリッジ回路で巻線２−１を除いたものがＵ相のパワーモジュール３−１であり、Ｖ相およびＷ相のパワーモジュール３−２、３−３も同じ構成であり、このようにスイッチング素子を用いて構成するＨ型ブリッジ回路のパワーモジュール３−１、３−２、３−３に接続される。
【００１０】
この各相のＨ型ブリッジ回路を構成するスイッチング素子の通電状態を制御し、モータ１を駆動する。スイッチング素子の通電状態は駆動波形出力部１２の出力によりドライバ部６を経由して、制御される。
【００１１】
電圧検出部（誘起電圧検出手段）５は、各相の巻線２−１、２−２、２−３の両端の電圧を検知し、レベル変換とノイズのフィルタリングをする。
【００１２】
センサレス制御部４は、外部よりモータ１を制御するための駆動波形デューティ指令値１３と電圧検出部５からの通電していない各相の誘起電圧値を入力し、必要なセンサレス制御のための処理を行い、モータ１の駆動に要求されるトルクと回転数を制御するために各巻線２−１〜２−３に流す電流を制御するために、各相のパワーモジュール３−１〜３−３のスイッチング素子の通電状態を制御するための駆動波形を出力する。また、センサレス制御部４は、通常マイクロコンピュータ１５とその周辺回路から構成され、そのマイクロコンピュータ１５の機能として、通電していない相に誘起する誘起電圧を選択的にＡＤ変換部７に供給する誘起電圧切替部１４、誘起電庄値をサンプリングし、デジタル値に変換するＡＤ変換部７、後述する誘起電圧の最初の頂点を見つける転流区間検出部（頂点検出手段）９、マップＡ８Ａからの閾値情報で位置切替(相切替)点を判断し、最新のロータ位置情報を出力するとともに回転数の演算を行う誘起電圧検出部（回転数検出手段）１０、外部からの駆動波形デューティ指令値１３に基づき必要なＰＷＭ信号を発生するＰＷＭ発生部１１とＰＷＭ発生部１１の出力とロータ位置情報からモータ１を駆動する駆動波形を発生する駆動波形出力部１２などを持つ。
【００１３】
本第１の実施の形態においては、位置切替点を判断するための第１の閾値（第１の所定の閾値、第２の所定の閾値）と第２の閾値（変化量閾値）を、モータ１の特性に合わせ予めマップとして表１のように用意しておく。なお、閾値はそれぞれ、誘起電圧が減少（増加から減少）方向の場合に使用する閾値と、増加（減少から増加）方向の場合に使用する２種類がある。
【００１４】
【表１】

次に本第１の実施の形態の動作について、図１〜１１および表１〜３を用いて説明する。
【００１５】
まず、通電していない相の巻線に発生する誘起電圧について説明する。一般的なＹ結線３相直流ブラシレスモータでは通電していない相以外の２つの相には完全に同一な電流が流れるが、６線式３相直流ブラシレスモータでは、図１のパワーモジュール３−１〜３−３に示すＨ型ブリッジで巻線２−１〜２−３を駆動するので、各巻線の抵抗違いや、駆動波形の違い等から通常、２つの相に流れる相電流が一致することは無い。一方通電していない相の巻線の端子電圧（相電圧）は、ロータ回転による誘起電圧と、他の通電中の相に流れる電流に起因して誘起する電圧の合成となるが、Ｙ結線３相直流ブラシレスモータでは他の通電中の相に流れる電流に起因して誘起する電圧はほぼ打ち消しあい大きな影響が無い。しかし、６線式３相直流ブラシレスモータでは、他の通電中の相に流れる電流に起因して誘起する電圧が、通電中の相に流れる電流の不一致から大きくなる。また、他の通電中の相に流れる電流に起因して誘起する電圧は通電中の相に流れる電流が大きいほど、すなわちモータの発生トルクが大きいほど大きくなる。
【００１６】
なお今後、誘起電圧とは特に断りの無い限り、通電していない相の巻線に発生するロータ回転による誘起電圧と、他の通電中の相に流れる電流に起因して誘起する電圧の合成電圧を意味する。
【００１７】
図２は６線式３相直流ブラシレスモータの相電流が小さい場合（微小トルク出力時）の各相の誘起電圧を示す。図２において、合成値とは各相の通電していない区間（図２中の円で囲んだ部分）に観測される誘起電圧のみを抜き出して得られた波形である。Ｙ結線３相直流ブラシレスモータではこの合成値の誘起電圧がゼロをクロスする点を検出し相の切替を行うのが一般的だが、６線式３相直流ブラシレスモータでは図３に示すように回転数の変動によって、ゼロクロス点が変動し、また図４に示すモータの発生トルクが小さいとき、図５に示すモータの発生トルクが中の時あるいは図６に示すようにモータの発生トルクが大きい場合に示すようにゼロクロス点が変動する。それゆえ、６線式３相ブラシレスモータではゼロクロス点検出による相切替は困難となる。なお、本第１の実施の形態では図３〜６に示すようにモータの特性に合わせ予めマップとして表１のマップＡを作成しておく。
【００１８】
次に図７に示すセンサレス制御部４に組み込まれているマイクロコンピュータ１５の動作の概要を示すフローチャートに基づき、本第１の実施の形態の全体的な動作を説明する。まず、電源が投入され、モータ１の運転をしようとするときは、初期設定Ｓ１５１により、必要な初期値の設定を行う。モータ１の起動時にはある程度の回転数に上昇するまで、誘起電圧を検出できないため、センサレス駆動方式では、一般的には同期駆動と呼ばれる各相の巻線２−１、２−２、２−３に順次電流を流すことにより発生する回転磁界により、ロータの強制回転を行う。同期駆動Ｓ１５２はこのための処理を示す。
【００１９】
同期駆動の方法について、図２および表２を用いて説明する。表２はモータ１のロータ位置と各相のパワーモジュール３−１、３−２、３−３のスイッチング状態を示す図である。ロータの強制回転は実回転数に依存しない所定のタイミングで現在位置（表２における位置１〜６）を順次駆動波形出力部１２に出力する。これにより、駆動波形出力部１２はドライバ部６を経由して、表２に示すように各相のパワーモジュール３−１、３−２、３−３のスイッチング素子をオン／オフ制御することにより、モータ１内に強制的に回転磁界を発生させ、ロータを回転させる。ロータが回転し、ある程度の回転数に達すると誘起電圧が検出可能になる。
【００２０】
【表２】

位置確定Ｓ１５３は、同期駆動のための各相のパワーモジュール３−１、３−２、３−３のスイッチング素子のオン／オフ制御を一旦停止させ、例えばＵ相の誘起電圧を検出し、誘起電圧が減少方向に変化している状態で、ゼロクロスが検出された場合は、現在位置を１にセットし、誘起電圧が増加方向に変化している状態で、ゼロクロスが検出された場合は、現在位置を４にセットする。所定の時間以内にゼロクロスが検出されなかった場合は、再度同期駆動を実施する。位置が確定した場合は、再度各相のパワーモジュール３−１、３−２、３−３のスイッチング素子のオン／オフ制御を再開し、位置切替検出ルーチンＳ１５５に移行する。なお、通常位置が切り替わった場合は、転流区間検出Ｓ１５４に移行するが、同期駆動後の位置確定時は各相のパワーモジュール３−１、３−２、３−３のスイッチング素子がオフしているため、転流電流が発生しないため、転流区間検出Ｓ１５４は実行しない。
【００２１】
転流区間検出Ｓ１５４は、誘起電圧検出において転流電流のため誘起電圧が検出不可能な区間を識別し、位置切替検出のためには使用しないようにするための手続きであり、その転流区間検出フローチャートを図８に示す。位置切替検出Ｓ１５５は、誘起電圧から位置の切り替え点の判断と回転数の算出を行う処理であり、その位置切替検出フローチャートを図９に示す。位置切替点が決まれば、現在位置の番号を１つ進め（Ｓ１５６）、その値を駆動波形出力部１２に出力する（Ｓ１５７）ことで、各相のパワーモジュール３−１、３−２、３−３のスイッチング素子のオン／オフ状態を次の位置の状態に変更する。これらの処理がモータ１の運転が終了するまでつづけられる。
【００２２】
次に転流区間検出について、図８および図１０の転流区間検出説明のための誘起電圧波形例を用いて説明する。誘起電圧の波形は概ね図１０に示すような波形であり、図１０に記載の誘起電圧ＡＤ値は図１のＡＤ変換部７の入力電圧を示している。図１０の誘起電圧波形の中でＴ１０１からＴ１０５、Ｔ１０４の区間や、Ｔ１０６からＴ１１０、Ｔ１０９の区間は転流電流の影響で誘起電圧が読めない区間であり、この区間を以下の手順で検出する。
【００２３】
まず図８において、現在のロータの位置（表２の位置１〜６）を判断（Ｓ１０２）し、処理を分岐する。現在の位置が１、３、５の場合は転流電流により相電圧は正電圧となり、誘起電圧は負からゼロ方向へ増加（増加方向、図１０の位置１）していく。転流区間の電圧は正となるため、誘起電圧値を入力する変数の初期値を負の最大値にセットする（Ｓ１０３、ここでは変数ＯＬＤ４、ＯＬＤ３、ＯＬＤ２を−１２８にセット）。次に誘起電圧を読み込み変数ＮＥＷに格納する（Ｓ１０４）。今読み込んだ値が直前の値（変数ＯＬＤ２に格納されている）と等しいかどうか判断し、等しい場合は今読み込んだ値を無視し、次の誘起電圧読み込みに戻り、新たな誘起電圧を読み取る。等しくない場合は次のＳ１０６に進む。ＮＥＷ＝ＯＬＤ２を判断するのは、頂点検出を確実にするためである。Ｓ１０６では４つの変数（ＯＬＤ４、ＯＬＤ３、ＯＬＤ２、ＮＥＷ）を比較し、ＯＬＤ３が最も小さいことを判断（条件：ＯＬＤ４＞ＯＬＤ３＜ＯＬＤ２＜ＮＥＷ）し、下向きの頂点となっていないか判断する。この条件が成立していない場合にはＳ１０７にてデータを更新し、誘起電圧読み取り（Ｓ１０４）に戻る。この手順により、４個の誘起電圧読み込み値を順次更新、比較していき、例えば図１０の波形において、ＯＬＤ４＝Ｔ１０５、ＯＬＤ３＝Ｔ１０４、ＯＬＤ２＝Ｔ１０３、ＮＥＷ＝Ｔ１０２のとき、Ｓ１０６の条件が成立し、Ｔ１０４（ＯＬＤ３）が頂点であることが検出できる。検出できた頂点の値（Ｔ１０４）を変数Ｖｍａｘに格納する（Ｓ１０８）。この頂点の値は図７における次の処理である位置切替検出Ｓ１５５で使用するためである。
【００２４】
現在の位置が２、４、６の場合には転流電流により相電圧は負電圧となり、誘起電圧は正からゼロ方向へ減少（減少方向、図１０の位置２）していき、転流区間の電圧は負となるため、誘起電圧値を入力する変数の初期値を正の最大値にセットする（Ｓ２０３、ここでは１２８にセット）のと、頂点検出条件（Ｓ２０６、条件：ＯＬＤ４＜ＯＬＤ３＞ＯＬＤ２＞ＮＥＷ）が異なるのみなので、位置が１、３、５の場合と同様の処理により上向きの頂点（図１０のＴ１０９）を検出する。
【００２５】
次に位置切替検出について、図９および図１１の位置切替動作説明のための誘起電圧波形例を用いて説明する。まず図１１に示す頂点Ｔ１１１の値が変数Ｖｍａｘに格納されているものとする。現在のロータ位置を判断（Ｓ１２０）し、処理を分岐する。現在の位置が１、３、５の場合は、誘起電圧は負からゼロ方向へ増加するため、処理はＳ１２１へ進む。位置切替の閾値となる第１の閾値、第２の閾値を決定するため表１のマップＡから第１の閾値の第１の所定の閾値、第２の閾値を読み取る（Ｓ１２１）。参照すべきマップアドレスは現在の回転数（直前の位置切替時間間隔から算出可能）と、外部より供給される駆動波形デューティ指令値（以下、デューティ値と称す）により決めることができる。ただ、一致する回転数やデューティ値が無い場合は、それらの値をマップＡの値に切り上げて、アドレスを決める。ここで誘起電圧は増加方向であるため、マップＡの増加側上限（第１の閾値の第１の所定の閾値）と増加側幅（第２の閾値）をそれぞれ読み取り変数ＵＰＭとＵＰＨに格納しておく。次に誘起電圧を読み込み、変数Ｖｎｅｗに格納する（Ｓ１２２）。しかる後、変数ＵＰＭ、ＵＰＨおよびＶｎｅｗを用いて、位置切替点にあるかどうか判断を実施する（Ｓ１２３）。判断条件は２つあり、１つは誘起電圧が第１の閾値の第１の所定の閾値以上を判断する。図１１ではＴ１１２が第１の閾値の第１の所定の閾値以上となった場合を示している。もう１つは転流区間検出Ｓ１５４にて検出した頂点（Ｓ１０８、Ｖｍａｘ＝ＯＬＤ３）と現在の誘起電圧値Ｖｎｅｗの差（Ｖｎｅｗ−Ｖｍａｘ）が第２の閾値以上であることを判断する。図１１ではＴ１１２−Ｔ１１１（＝Ｔ１１３）が第２の閾値以上となった場合を示している。
【００２６】
次に、現在の位置が２、４、６の場合、まず図１１に示す頂点Ｔ１１４の値が変数Ｖｍａｘに格納されているものとする。誘起電圧は正からゼロ方向へ減少するため、処理はＳ２２１へ進む。位置切替の閾値となる第１の閾値、第２の閾値を決定するため表１のマップＡから第１の閾値の第２の所定の閾値、第２の閾値を読み取る（Ｓ２２１）。参照すべきマップアドレスは現在の回転数（直前の位置切替時間間隔から算出可能）と、デューティ値により決めることができる。ただ、一致する回転数やデューティ値が無い場合は、それらの値をマップＡの値に切り上げて、アドレスを決める。ここで誘起電圧は減少方向であるため、マップＡの減少側下限（第１の閾値の第２の所定の閾値）と減少側幅（第２の閾値）をそれぞれ読み取り変数ＤＯＷＮＭとＤＯＷＮＨに格納しておく。次に誘起電圧を読み込み、変数Ｖｎｅｗに格納する（Ｓ２２２）。しかる後、変数ＤＯＭＮＭ、ＤＯＭＮＨおよびＶｎｅｗを用いて、位置切替点にあるかどうか判断を実施する（Ｓ２２３）。判断条件は２つあり、１つは誘起電圧が第１の閾値の第２の所定の閾値以下を判断する。図１１ではＴ１１５が第１の閾値の第２の所定の閾値以下となった場合を示している。もう１つは転流区間検出Ｓ１５４にて検出した頂点（Ｓ１０８、Ｖｍａｘ＝ＯＬＤ３）と現在の誘起電圧値Ｖｎｅｗの差（Ｖｍａｘ−Ｖｎｅｗ）が第２の閾値以上であることを判断する。図１１ではＴ１１４−Ｔ１１５（＝Ｔ１１６）が第２の閾値以上であることを示している。これら２つの判断条件の内、いずれかが成立すれば位置切替点であると判断する。
【００２７】
なお、これら２つの判断条件のうち１つだけを用いて位置切替点を判断することもできることは明らかである。
【００２８】
以上述べたごとく本第１の実施の形態によれば、モータトルク量（デューティ値）、回転数によって誘起電圧が変動する６線式３相直流ブラシレスモータにおいても、誘起電圧の頂点を検出し、閾値以上、以下で位置切替えを行うことにより、センサレス駆動方式が可能となる。そのためロータ位置検出装置が不要となり、ロータ位置検出装置とモータを制御するインバータ制御回路等の間を接続するハーネスが不要となり、簡単な誘起電圧検出回路と制御方式により、低価格のセンサレス駆動方式を提供できる。
【００２９】
次に本発明の第２の実施の形態について述べる。本第２の実施の形態はアイドルストップ車のエンジンスタート時に適用した場合である。エンジンスタート時にはモータ１を最大トルクで使用するため、使用するモータ１の各回転数の最大トルクを出力するデューティ値の閾値（第１の閾値、第２の閾値）のみを持っておればよい。それ由、閾値のマップは表３のマップＢに示すように最大のデューティ値の閾値のマップＢを持たせればよい。
【００３０】
【表３】

また、第２の実施の形態の全体的な構成を示す概略図を図１２に示すが、図１と大きく異なるところはモータ１を最大トルクで使用するため、外部からの駆動波形デューティ指令値１３がいらないことで、それ以外は図１と同じである。
【００３１】
本第２の実施の形態においては、閾値は回転数のみによって決まるため、閾値を一次元のマップにすることができるため、メモリや演算時間を大幅に削減できる。
【図面の簡単な説明】
【図１】第１の実施の形態の概略的な全体構成を示す構成図。
【図２】理想的な６線式３相直流ブラシレスモータの誘起電圧波形。
【図３】回転数別誘起電圧オフセット変化を示す図。
【図４】力行時（トルク小）の誘起電圧波形。
【図５】力行時（トルク中）の誘起電圧波形。
【図６】力行時（トルク大）の誘起電圧波形。
【図７】第１の実施の形態の全体的な動作の概要を示すフローチャート。
【図８】転流区間検出フローチャート。
【図９】位置切替検出フローチャート。
【図１０】転流区間検出説明のための誘起電圧波形例。
【図１１】位置切替検出説明のための誘起電圧波形例。
【図１２】第２の実施の形態の概略的な全体構成を示す構成図。
【符号の説明】
Ｕ_Ｌ_Ｈ、Ｕ_Ｒ_Ｈ、Ｖ_Ｌ_Ｈ、Ｖ_Ｒ_Ｈ、Ｗ_Ｌ_Ｈ、Ｗ_Ｒ_Ｈ…上アーム側スイッチ
Ｕ_Ｌ_Ｌ、Ｕ_Ｒ_Ｌ、Ｖ_Ｌ_Ｌ、Ｖ_Ｒ_Ｌ、Ｗ_Ｌ_Ｌ、Ｗ_Ｒ_Ｌ…下アーム側スイッチ
１…直流ブラシレスモータ
２−１、２−２、２−３…電機子巻線
３−１、３−２、３−３…Ｈ型ブリッジ回路のパワーモジュール
５…電圧検出部
８Ａ…マップＡ
８Ｂ…マップＢ
９…転流区間検出部
１０…誘起電圧検出部
１３…駆動波形デューティ指令値
１６…駆動用電源[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a DC brushless motor control device that drives a DC brushless motor without a sensor.
[0002]
[Prior art]
[Patent Literature]
Japanese Patent Laid-Open No. 2000-236691.
[0003]
In the above-mentioned patent document, as a sensorless drive method for a general Y-connected DC brushless motor, an induced voltage induced in a non-energized phase is detected, and a zero-cross point of the induced voltage is detected to determine a phase to be energized. The timing for switching was determined.
[0004]
[Problems to be solved by the invention]
In this conventional zero cross point detection method, in a DC three-phase brushless motor (hereinafter referred to as a six-wire three-phase brushless motor) having an H-type bridge circuit for each of the three phases, it is induced in a non-energized phase. The induced voltage to be generated is a combination of the original induced voltage induced in the non-energized phase in the Y-connected DC three-phase brushless motor and the voltage induced by the mismatch of the current flowing in the other energized phase. There was a problem that the zero-cross point shifted and the phase switching point shifted.
[0005]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a DC brushless motor control device that can perform accurate phase switching even with a six-wire three-phase brushless motor.
[0006]
[Means for Solving the Problems]
In order to achieve this object, in the present invention, the induced voltage detecting means for detecting the induced voltage generated in the armature winding of the phase that is not energized, and the induced voltage detected by the induced voltage detecting means are increased. The vertex detection means for detecting that the change from the decrease to the increase or the decrease to the increase, and the change in the induced voltage when the induced voltage decreases from the increase or decreases to the increase by the vertex detection means It was set as the structure provided with the phase switching means which switches an energized phase when it becomes more than a quantity threshold value.
[0007]
【The invention's effect】
According to the present invention, the induced voltage detecting means for detecting the induced voltage generated in the phase that is not energized, and the vertex detecting means for detecting that the detected induced voltage has decreased from increasing or decreased to increasing. The energized phase can be accurately switched by the phase switching means for switching the energized phase when the amount of change in the induced voltage from when the induced voltage decreases or increases from the apex becomes equal to or greater than a predetermined change amount threshold. .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof is omitted.
[0009]
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a schematic overall configuration of a first embodiment of the present invention. The configuration of the first embodiment will be described with reference to FIG. A 6-wire three-phase brushless motor (hereinafter referred to as a motor) 1 includes U, V, and W phase armature windings (hereinafter referred to as windings) 2-1, 2-2, 2- 3 and a permanent magnet (not shown) as a rotor. For example, in the U phase, the windings 2-1, 2-2, and 2-3 of each phase have upper arm side switching elements (using IGBT in FIG. 1) U_L_H, one of which is connected to the driving power supply 16. An H-type bridge circuit in which U_R_H and lower arm side switching elements U_L_L and U_R_L, one of which is grounded, are connected in series with each other and their connection midpoints are connected via winding 2-1. The U-phase power module 3-1 is obtained by removing the winding 2-1 in the H-type bridge circuit, and the V-phase and W-phase power modules 3-2 and 3-3 have the same configuration. Yes, and connected to the power modules 3-1, 3-2, and 3-3 of the H-type bridge circuit configured using the switching elements in this way.
[0010]
The energization state of the switching elements constituting the H-type bridge circuit of each phase is controlled to drive the motor 1. The energization state of the switching element is controlled by the output of the drive waveform output unit 12 via the driver unit 6.
[0011]
The voltage detection unit (induced voltage detection means) 5 detects voltages at both ends of the windings 2-1, 2-2, and 2-3 of each phase, and performs level conversion and noise filtering.
[0012]
The sensorless control unit 4 inputs a drive waveform duty command value 13 for controlling the motor 1 from the outside and an induced voltage value of each non-energized phase from the voltage detection unit 5, and performs processing for necessary sensorless control. In order to control the current that flows through the windings 2-1 to 2-3 in order to control the torque and rotational speed required for driving the motor 1, the power modules 3-1 to 3-3 of each phase A drive waveform for controlling the energization state of the switching element is output. The sensorless control unit 4 is usually composed of a microcomputer 15 and its peripheral circuits. As the function of the microcomputer 15, an induction voltage that selectively induces an induced voltage in a phase that is not energized is supplied to the AD conversion unit 7. Voltage switching unit 14, AD conversion unit 7 that samples the induced voltage value and converts it to a digital value, a commutation section detection unit (vertex detection means) 9 that finds the first vertex of the induced voltage described later, and a threshold value from map A8A The position switching (phase switching) point is determined from the information, the latest rotor position information is output and the rotational speed is calculated, and the induced voltage detection unit (rotational speed detection means) 10 and the external drive waveform duty command value 13 Based on the PWM generator 11 for generating a necessary PWM signal based on the output of the PWM generator 11 and the rotor position information, a drive waveform for driving the motor 1 is generated. With such waveform output section 12.
[0013]
In the first embodiment, a first threshold value (first predetermined threshold value, second predetermined threshold value) and a second threshold value (change amount threshold value) for determining a position switching point are set as motors. A map as shown in Table 1 is prepared in advance according to the characteristics of 1. There are two types of threshold values, one used when the induced voltage is decreasing (decreasing from increasing) and the other being used when the induced voltage is increasing (decreasing from increasing).
[0014]
[Table 1]

Next, the operation of the first embodiment will be described with reference to FIGS.
[0015]
First, an induced voltage generated in a winding of a phase that is not energized will be described. In a general Y-connected three-phase DC brushless motor, the same current flows in two phases other than the non-energized phase. However, in a six-wire three-phase DC brushless motor, the power module 3-1 in FIG. Since the windings 2-1 to 2-3 are driven by the H-shaped bridge shown in 3-3, the phase currents that normally flow in the two phases must match because of differences in resistance of each winding, differences in driving waveforms, etc. There is no. On the other hand, the terminal voltage (phase voltage) of the winding of the non-energized phase is a combination of the induced voltage due to the rotor rotation and the voltage induced due to the current flowing in the other energized phase. In the phase DC brushless motor, the voltage induced due to the current flowing in the other energized phase almost cancels and there is no great influence. However, in the 6-wire three-phase DC brushless motor, the voltage induced due to the current flowing in the other current-carrying phase is increased due to the mismatch of the current flowing in the current-carrying phase. In addition, the voltage induced due to the current flowing in the other energized phase increases as the current flowing in the energized phase increases, that is, the generated torque of the motor increases.
[0016]
In the future, unless otherwise specified, the induced voltage is the combined voltage of the induced voltage due to the rotor rotation generated in the winding of the non-energized phase and the voltage induced due to the current flowing in the other energized phase. Means.
[0017]
FIG. 2 shows the induced voltage of each phase when the phase current of the 6-wire 3-phase DC brushless motor is small (at the time of minute torque output). In FIG. 2, the composite value is a waveform obtained by extracting only the induced voltage observed in the section where each phase is not energized (portion surrounded by a circle in FIG. 2). In a Y-connected 3-phase DC brushless motor, it is common to detect the point where the induced voltage of this composite value crosses zero and to switch phases, but in a 6-wire 3-phase DC brushless motor, rotation is performed as shown in FIG. When the zero-crossing point fluctuates due to fluctuations in the number, when the generated torque of the motor shown in FIG. 4 is small, when the generated torque of the motor shown in FIG. 5 is medium, or when the generated torque of the motor is large as shown in FIG. As shown, the zero cross point fluctuates. Therefore, in the 6-wire three-phase brushless motor, it is difficult to switch phases by detecting the zero cross point. In the first embodiment, as shown in FIGS. 3 to 6, a map A in Table 1 is created in advance as a map in accordance with the characteristics of the motor.
[0018]
Next, the overall operation of the first embodiment will be described based on a flowchart showing an outline of the operation of the microcomputer 15 incorporated in the sensorless control unit 4 shown in FIG. First, when the power is turned on and the motor 1 is to be operated, necessary initial values are set in the initial setting S151. Since the induced voltage cannot be detected until the number of rotations is increased to a certain number of revolutions when the motor 1 is started, in the sensorless driving method, the windings 2-1 2-2, 2-3 of each phase generally called synchronous driving are used. The rotor is forcibly rotated by a rotating magnetic field generated by sequentially passing current through the rotor. The synchronous drive S152 shows the process for this.
[0019]
A method of synchronous driving will be described with reference to FIG. Table 2 shows the rotor position of the motor 1 and the switching states of the power modules 3-1, 3-2 and 3-3 for each phase. The forced rotation of the rotor sequentially outputs the current position (positions 1 to 6 in Table 2) to the drive waveform output unit 12 at a predetermined timing that does not depend on the actual rotational speed. Thus, the drive waveform output unit 12 performs on / off control of the switching elements of the power modules 3-1, 3-2, and 3-3 of each phase as shown in Table 2 via the driver unit 6. Then, a rotating magnetic field is forcibly generated in the motor 1 to rotate the rotor. When the rotor rotates and reaches a certain number of rotations, the induced voltage can be detected.
[0020]
[Table 2]

The position determination S153 temporarily stops the on / off control of the switching elements of the power modules 3-1, 3-2, 3-3 of each phase for synchronous driving, and detects, for example, an induced voltage of the U phase. If the zero cross is detected while the voltage is changing in the decreasing direction, the current position is set to 1. If the zero cross is detected while the induced voltage is changing in the increasing direction, the current position is set. Set the position to 4. If no zero cross is detected within a predetermined time, synchronous driving is performed again. When the position is fixed, the on / off control of the switching elements of the power modules 3-1, 3-2, 3-3 of each phase is resumed, and the process proceeds to the position switching detection routine S155. When the normal position is switched, the process proceeds to the commutation section detection S154. However, when the position is determined after the synchronous drive, the switching elements of the power modules 3-1, 3-2, and 3-3 of each phase are turned off. Therefore, since no commutation current is generated, the commutation section detection S154 is not executed.
[0021]
The commutation section detection S154 is a procedure for identifying a section in which the induced voltage cannot be detected due to the commutation current in the induced voltage detection and not using it for position switching detection. A detection flowchart is shown in FIG. The position switching detection S155 is a process for determining the position switching point and calculating the rotation speed from the induced voltage, and a position switching detection flowchart is shown in FIG. When the position switching point is determined, the current position number is incremented by 1 (S156), and the value is output to the drive waveform output unit 12 (S157), whereby the power modules 3-1, 3-2, 3 of each phase are output. 3 is changed to the state of the next position. These processes are continued until the operation of the motor 1 is completed.
[0022]
Next, commutation section detection will be described using an example of an induced voltage waveform for explaining commutation section detection in FIGS. 8 and 10. The waveform of the induced voltage is generally as shown in FIG. 10, and the induced voltage AD value shown in FIG. 10 indicates the input voltage of the AD converter 7 in FIG. In the induced voltage waveform of FIG. 10, the sections from T101 to T105 and T104 and the sections from T106 to T110 and T109 are sections where the induced voltage cannot be read due to the influence of the commutation current, and this section is detected by the following procedure. .
[0023]
First, in FIG. 8, the current rotor position (positions 1 to 6 in Table 2) is determined (S102), and the process branches. When the current position is 1, 3, or 5, the phase voltage becomes positive due to the commutation current, and the induced voltage increases from negative to zero (increase direction, position 1 in FIG. 10). Since the voltage in the commutation section is positive, the initial value of the variable for inputting the induced voltage value is set to the negative maximum value (S103, here, the variables OLD4, OLD3, and OLD2 are set to −128). Next, the induced voltage is read and stored in the variable NEW (S104). It is determined whether or not the read value is equal to the previous value (stored in the variable OLD2). If the read value is equal, the read value is ignored, the next induced voltage reading is returned, and a new induced voltage is read. When not equal, it progresses to following S106. The reason for determining NEW = OLD2 is to ensure vertex detection. In S106, four variables (OLD4, OLD3, OLD2, and NEW) are compared, and it is determined that OLD3 is the smallest (condition: OLD4> OLD3 <OLD2 <NEW), and it is determined whether or not the vertex is downward. If this condition is not satisfied, the data is updated in S107, and the process returns to the induced voltage reading (S104). By this procedure, four induced voltage read values are sequentially updated and compared. For example, when OLD4 = T105, OLD3 = T104, OLD2 = T103, and NEW = T102 in the waveform of FIG. 10, the condition of S106 is satisfied. Then, it can be detected that T104 (OLD3) is the apex. The detected vertex value (T104) is stored in the variable Vmax (S108). This vertex value is used in the position switching detection S155 which is the next process in FIG.
[0024]
When the current position is 2, 4, or 6, the phase voltage becomes negative due to the commutation current, and the induced voltage decreases from positive to zero (decrease direction, position 2 in FIG. 10). Since the initial value of the variable for inputting the induced voltage value is set to a positive maximum value (S203, set to 128 in this case), the vertex detection condition (S206, condition: OLD4 <OLD3>) Since only OLD2> NEW) is different, an upward vertex (T109 in FIG. 10) is detected by the same processing as in the case of

positions

1, 3, and 5.
[0025]
Next, position switching detection will be described using an example of an induced voltage waveform for explaining the position switching operation in FIGS. 9 and 11. First, it is assumed that the value of the vertex T111 shown in FIG. 11 is stored in the variable Vmax. The current rotor position is determined (S120), and the process branches. If the current position is 1, 3, or 5, the induced voltage increases from negative to zero, so the process proceeds to S121. In order to determine the first threshold value and the second threshold value as the position switching threshold values, the first predetermined threshold value and the second threshold value of the first threshold value are read from the map A in Table 1 (S121). The map address to be referred to can be determined by the current rotational speed (which can be calculated from the immediately preceding position switching time interval) and a drive waveform duty command value (hereinafter referred to as duty value) supplied from the outside. However, if there is no coincident rotation speed or duty value, those values are rounded up to the values of map A to determine the address. Here, since the induced voltage is increasing, the upper limit (first predetermined threshold of the first threshold) and the increased width (second threshold) of map A are stored in the reading variables UPM and UPH, respectively. Keep it. Next, the induced voltage is read and stored in the variable Vnew (S122). Thereafter, using the variables UPM, UPH, and Vnew, it is determined whether or not the position is at the position switching point (S123). There are two determination conditions. One is to determine whether the induced voltage is equal to or higher than the first predetermined threshold of the first threshold. FIG. 11 shows a case where T112 is equal to or greater than a first predetermined threshold value of the first threshold value. The other is to determine that the difference (Vnew−Vmax) between the apex (S108, Vmax = OLD3) detected in the commutation section detection S154 and the current induced voltage value Vnew is greater than or equal to the second threshold. FIG. 11 shows a case where T112−T111 (= T113) is equal to or greater than the second threshold.
[0026]
Next, when the current position is 2, 4, or 6, it is assumed that the value of the vertex T114 shown in FIG. 11 is stored in the variable Vmax. Since the induced voltage decreases from positive to zero, the process proceeds to S221. In order to determine the first threshold value and the second threshold value, which are the position switching threshold values, the second predetermined threshold value and the second threshold value of the first threshold value are read from the map A in Table 1 (S221). The map address to be referred to can be determined by the current rotation speed (which can be calculated from the immediately preceding position switching time interval) and the duty value. However, if there is no coincident rotation speed or duty value, those values are rounded up to the values of map A to determine the address. Here, since the induced voltage is in a decreasing direction, the decreasing lower limit (second predetermined threshold of the first threshold) and the decreasing width (second threshold) of map A are stored in the reading variables DOWNNM and DOWNH, respectively. Keep it. Next, the induced voltage is read and stored in the variable Vnew (S222). Thereafter, using the variables DOMNM, DOMNH, and Vnew, it is determined whether or not the position is at the position switching point (S223). There are two determination conditions. One is to determine whether the induced voltage is equal to or lower than a second predetermined threshold value of the first threshold value. FIG. 11 shows a case where T115 is equal to or less than the second predetermined threshold value of the first threshold value. The other is to determine that the difference (Vmax−Vnew) between the apex (S108, Vmax = OLD3) detected in the commutation section detection S154 and the current induced voltage value Vnew is equal to or greater than the second threshold. FIG. 11 shows that T114−T115 (= T116) is greater than or equal to the second threshold value. If any of these two determination conditions is satisfied, it is determined that the position is a position switching point.
[0027]
It is obvious that the position switching point can be determined using only one of these two determination conditions.
[0028]
As described above, according to the first embodiment, even in a 6-wire three-phase DC brushless motor in which the induced voltage varies depending on the motor torque amount (duty value) and the rotational speed, the peak of the induced voltage is detected, By performing position switching between the threshold value and the threshold value, a sensorless driving method is possible. This eliminates the need for a rotor position detection device, eliminates the need for a harness that connects the rotor position detection device and an inverter control circuit that controls the motor, and provides a low-cost sensorless drive system with a simple induced voltage detection circuit and control method. Can be provided.
[0029]
Next, a second embodiment of the present invention will be described. The second embodiment is applied when the engine of an idle stop vehicle is started. Since the motor 1 is used with the maximum torque when the engine is started, it is only necessary to have a threshold value of the duty value (first threshold value, second threshold value) for outputting the maximum torque at each rotation speed of the motor 1 to be used. Therefore, the threshold map may have a maximum duty value threshold map B as shown in map B of Table 3.
[0030]
[Table 3]

FIG. 12 is a schematic diagram showing the overall configuration of the second embodiment. The difference from FIG. 1 is that the motor 1 is used with the maximum torque, so that the drive waveform duty command value 13 from the outside is used. Otherwise, it is the same as FIG.
[0031]
In the second embodiment, since the threshold value is determined only by the rotation speed, the threshold value can be made a one-dimensional map, so that the memory and calculation time can be greatly reduced.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a schematic overall configuration of a first embodiment.
FIG. 2 shows an induced voltage waveform of an ideal 6-wire 3-phase DC brushless motor.
FIG. 3 is a diagram showing changes in induced voltage offset by rotation speed.
FIG. 4 shows an induced voltage waveform during power running (small torque).
FIG. 5 shows an induced voltage waveform during power running (during torque).
FIG. 6 shows an induced voltage waveform during power running (large torque).
FIG. 7 is a flowchart showing an overview of the overall operation of the first embodiment.
FIG. 8 is a commutation section detection flowchart.
FIG. 9 is a position switching detection flowchart.
FIG. 10 shows an example of an induced voltage waveform for explaining commutation section detection.
FIG. 11 shows an example of an induced voltage waveform for explaining position switching detection.
FIG. 12 is a configuration diagram showing a schematic overall configuration of a second embodiment.
[Explanation of symbols]
U_L_H, U_R_H, V_L_H, V_R_H, W_L_H, W_R_H ... Upper arm side switch U_L_L, U_R_L, V_L_L, V_R_L, W_L_L, W_R_L ... Lower arm side switch 1 ... DC brushless motors 2-1, 2-2, 2-3 ... Electric Child windings 3-1, 3-2, 3-3 ... power module 5 of H-type bridge circuit ... voltage detector 8A ... map A
8B ... Map B
9 ... Commutation section detector 10 ... Induced voltage detector 13 ... Drive waveform duty command value 16 ... Drive power supply

Claims

Two series circuits in which the upper arm side switching element and the lower arm side switching element are connected in series are connected in parallel, and the connection midpoints of the upper arm side switching element and the lower arm side switching element are connected to each other via a winding. A 6-wire system that is driven by the H-type bridge circuit that is provided for each of the three phases, the upper arm side switching element is connected to a power source, and the lower arm side switching element is grounded In the three-phase brushless motor control device,
Induced voltage detection means for detecting the induced voltage generated in the non-energized phase;
A vertex detection means for detecting that the induced voltage detected by the induced voltage detection means has decreased from an increase or has decreased to an increase;
Phase switching means for switching the energized phase when the amount of change in the induced voltage from the time when the induced voltage is decreased from increase or decreased to increased by the vertex detection means is equal to or greater than a predetermined change amount threshold;
A six-wire three-phase brushless motor control device.

Two series circuits in which the upper arm side switching element and the lower arm side switching element are connected in series are connected in parallel, and the connection midpoints of the upper arm side switching element and the lower arm side switching element are connected to each other via a winding. H-bridge circuit connected with each phase of the three phases Te, the upper arm switching element is connected to a power supply, 6-wire the lower arm switching elements you driven by the H-bridge circuit that is grounded In the three-phase brushless motor control device,
An induced voltage detection hand throw that detects an induced voltage generated in a non-energized phase;
A vertex detection means for detecting that the induced voltage detected by the induced voltage detection means has decreased from an increase or has decreased to an increase;
When the induced voltage after the time when the induced voltage is changed from increase to decrease by the vertex detection means becomes less than a first predetermined threshold, or after the time when the induced voltage is changed from decrease to increase Phase switching means for switching the energized phase when the voltage is equal to or higher than a second predetermined threshold;
6-wire type three-phase brushless motor control device.

Two series circuits in which the upper arm side switching element and the lower arm side switching element are connected in series are connected in parallel, and the connection midpoints of the upper arm side switching element and the lower arm side switching element are connected to each other via a winding. A 6-wire system that is driven by the H-type bridge circuit that is provided for each of the three phases, the upper arm side switching element is connected to a power source, and the lower arm side switching element is grounded In the three-phase brushless motor control device,
Induced voltage detection means for detecting the induced voltage generated in the non-energized phase;
A vertex detection means for detecting that the induced voltage detected by the induced voltage detection means has decreased from an increase or has decreased to an increase;
When the induced voltage changes from an increase to a decrease or an increase from the decrease to an increase by the vertex detection means, or the induced voltage changes from an increase to a decrease. When the induced voltage after the turning point becomes equal to or less than a first predetermined threshold value, or when the induced voltage after the point when the induced voltage turns from increasing to increasing becomes equal to or more than a second predetermined threshold value. Phase switching means for switching the energized phase to
A six-wire three-phase brushless motor control device.

Rotational speed detection means for detecting the rotational speed of the 6-wire three-phase brushless motor is provided, and the change amount threshold value, the first predetermined threshold value, and the second predetermined threshold value of the induced voltage are detected by the rotational speed detection. The six-wire three-phase brushless motor control device according to any one of claims 1 to 3, wherein the control device is set based on the number of rotations detected by the means.

Comprising a to that rotation speed detecting hand stage detects the number of rotation 6-wire three-phase brushless motor, said change amount threshold of the induced voltage, said first predetermined threshold and the second predetermined threshold, The six-wire three-phase brushless motor control device according to any one of claims 1 to 3, wherein the controller is set based on the rotation number and the duty value detected by the rotation number detection means.